Of all the records and milestones Novak Djokovic has amassed over his incomparable career, the one achieved after winning the French Open title on Sunday probably tops the lot.
Djokovic, 34, is now just the third male player in history, and first in 52 years, to win all four Grand Slam titles twice, following in the footsteps of Roy Emerson and Rod Laver, and therefore making him the only player in the Open era.
Not even the Serb's great rivals Rafael Nadal and Roger Federer, against whom all of his successes are constantly compared, have achieved such a feat.
It speaks to Djokovic's relentless consistency and chameleon-like adaptability; his bottomless powers of reserve and his unwavering self-belief. Not to mention his quite ridiculous levels of skill and stamina.
As history shows, records like this don't come easy and Djokovic needed to summon all of his powers to get over the line against Stefanos Tsitsipas in a riveting final.
"It's a dream come true," Djokovic said, but at one point it was turning into a nightmare.
The top seed, whose previous title in Paris came in 2016, encountered over the net an unfazed opponent who not only went to battle with Djokovic but after two sets looked like he would win the war.
Tsitsipas may have been competing in his first major final, and he may have been carrying the hopes of a nation desperately hoping to see their first ever Grand Slam champion, but he took it all in his stride.
The Greek shrugged off a couple of early break points to find his groove and even after going down a break to allow Djokovic the opportunity to serve for the first set, fought back to level and take the tie-break.
Entering the second set, the trademark Djokovic response was nowhere to be seen. He was out of sorts, his timing was off, and he was constantly rubbing his eyes in some sort of discomfort. In contrast, Tsitsipas was firing on all cylinders and raced into a two-set lead thanks to breaks in the first and seventh games.
Djokovic darted off into the stadium for a comfort break and a change of shirt. He re-emerged decked out in red and as a player transformed.
Like Tiger Woods on a Sunday charge, the Serb went hunting. He rediscovered the level and intensity that guided him past defending champion Rafael Nadal in the semi-finals and earned the only break of the third set in the fourth game to claw his way back into the contest.
The momentum had well and truly shifted and once Djokovic stormed into a 4-0 lead in the fourth set, there was only going to be one winner. The roles had now been reversed. It was Tsitsipas' turn to face an onslaught but unlike Djokovic, he was unable to wrestle back control. Djokovic simply wouldn't allow it.
Physical and mental fatigue had set in for Tsitsipas - something Djokovic rarely experiences - and he was left with an impossible mountain to climb when the world No 1 went up a break in the third game of the final set.
Djokovic was in no mood to relinquish his advantage and he sealed his place in the history books after four hours and 11 minutes having claimed a 6-7, 2-6, 6-3, 6-2, 6-4 victory.
"It was an electric atmosphere. I want to thank my coach and my physio, everyone who has been with me on this journey," Djokovic said.
"I have played almost nine hours over the last 48 hours against two great champions, it was really tough physically over the last three days, but I trusted in my capabilities and knew I could do it."
For Tsitsipas, it was a heartbreaking Grand Slam final debut, but as one of the brightest talents on the ATP Tour, the 22-year-old will surely create plenty of happy memories on the biggest stages.
"It was a big fight out there, I tried my best and did as much as I could," an emotionally spent Tsitsipas said. "It was a good first time playing here in the finals, I had a good run and I'm happy with myself."
Djokovic, meanwhile, leaves Paris with a 19th Grand Slam title, with nine coming at the Australian Open, five at Wimbledon, three at the US Open, and now two at Roland Garros. He is just one behind the joint-record held by Nadal and Federer. Few would put it past him to surpass their tally sooner rather than later.
In fact, given the way Djokovic continues to redefine tennis, there will be no surprise if he one day strikes out on his own as the only three-time career Grand Slam champion.